Improvement in car-springs



G. M. HIGGINSON. Gar-.Sprin'g.

No. 205,269. Patented June 25,1878.

i Illlli v lllllb N:FETRS. PHOTD-LITHOGRAPHER. WASHXNGTON D C,

zUNlTnnsrArns PATENT "OFFICE.

oHARLns M. HIeeINsoiv, or CHICAGO, ILLINOIS.

I .IMPROVEMENT. ZIVN CAR-SPRINGS.

Specification forming part of Letters Patent No. 205,269, dated June 25,18 78 application filed June 28, 1877. i I

To all whom it may concern:

Be it known that I, CHARLES M. HIGGIN- soN, of Chicago, in the county ofCook and State of Illinois, have invented certain new and usefulImprovements in Oar-Sprin gs and I do hereby declare that the followingis a full, clear, and exact description thereof, which will enableothers skilled in the art to which it appertains to make and use thesame, reference being had to the accompanying drawings, and to theletters of reference marked thereon, which form a part of thisspecification.

My invention relates to that class of springs known as nest-springs,made of spiral coils of diflerent thicknesses of metal, arranged onewithin the other.

Nest-springs, as usually constructed heretofore, are defective, for thereason that they have generally been formed of coils from rods or barsof different lengths and with spirals of different degrees ofinclination, the consequence of which is that their resistance tocompression is not relatively uniform, and some one of them must bebrought to a bearing before the others, thereby causing it to supportthe whole weight or thrust of the car, and hence liable to become brokenor weakened, while the others are still capable of further compression,but are restrained from the further exertion of what should otherwise bean increasing resistance to the downward thrust of the car by reason ofthe fixed resistance of the other.

I have discovered that by constructing nestsprings in accordance withthe following conditions the difficulties above specified are entirelyobviated, to wit: First, that each of the spiral coils shall be formedfrom rods or bars of equal length; secondly, that the thickness or widthof each rod or bar from which the different coils are made shall, intheir plane of compression, each be relatively proportioned to the outerdiameter of their coils-that is to say, if the diameter of any one ofthe coils shall be, say, as four to one to the thickness of its rod orbar, then the diameters of all the other coils must respectively bearthe same ratio to the thickness of their bars, and so, if the standardratio assumed should be as five to one, or as three and ahalf to one,then each of the coils used must bear the same ratio between theirdiameter and the thickness of their bars; and, lastly, each rod, "onbeing lected as the standard angle on which they are.

to be spirally coiled, then each must be coiled on vthe same angle, andso, if an angle of sixty degrees, or any other angle, should beselected, then all must be made to conform to the same angle, and eachof the coils be of the same height.

In the accompanying drawings, Figure 1 represents the: bars from whichthe springs are made, said bars being of uniform length, though ofdifferent thicknesses, and they may be made square or oblong in theircross-section, or round, or in the form of rods, as found mostconvenient or desirable. Fig. 2 represents a spiral nest-spring madefrom bars 0blong intheir cross-section. Figs. 3, 4, and 5 are detachedviews of theseveral coils or spirals of which the nest-springrepresented by Fig. 2 is composed. Fig. 6 represents a nestspring madefrom round bars or rod metal. Figs. 7,8, and 9 are detached views of theseveral coils or spirals of which the nest-sprin g shown by Fig. 6 iscomposed.

As shown by these figures, the ends of the coils are made tapering, andI prefer to have them so made; but the ends may be left of full size, orof equal diameter with the rest of the coils, as shown by Fig. 10 of thedrawings.

The bars from which the coils are made are all of the same length, butvary in thickness or diameter, the outer spiral being of greaterthickness than the inner, as clearly shown by the drawings.

By making the coils from bars of equal length, and making the coilsthemselves of" the samelength or height, I secure uniform motion of allthe parts of the nest-spring, giving ease to the springs when used undercars, and insure such proportions between the spirals and the loads eachwill bear as to avoid weakening or breaking the inner spirals-a frequentoccurrence with the springs heretofore in use, the inner and smallersprings heretofore used being of a sharper pitch and made from longerbars than the outer coils or spirals.

The most perfect way of operating my invention is to proportion in anyratio the width or cross-section of the bars in the line of compressionto the outside diameter-of the coil, and the proportion so adoptedshould be adhered to in constructing. all the coils. If the ratio soused shall not be exactly proportionate, either in anyone of the coilsor between the several coils, but shall be nearly so, the result will bepractically the same.

It is found that the desired result is practically obtained by simplymaking the bars of equal length before coiling, and respectivelyproportioning them in their width to the out- "side diameter of theircoils, as above described.

In testimony that I claim the foregoing as I my own I afiix my signaturein presence of two witnesses.

' CHAS. M. HIGGINSON.

Witnesses:

D. B. SIBLEY, SAlVL L. OHARLEs.

